Alternate action switches are toggle switches which can make alternate electrical connections upon actuation. These switches are used in, for example, automotive applications for functions such as headlight beam change and hazard warning lights.
Referring to FIG. 1A, a conventional alternate action switch 10 includes a two piece housing 12, a two state switching device 14, an actuator mechanism 16, and a user interface (not shown).
The housing 12 supports the components of the switch 10. When the pieces of the housing 12 are joined a chamber 20 and a bore 22 are formed. Each piece of the housing 12 has a hole 24 disposed therethrough. A translational axis TA extends through the center of the bore 22. An operational axis OA extends through the holes 24. The operational axis OA is perpendicular to the translational axis TA.
The switching device 14 is mounted within the chamber 20 of the housing 12, and has two states which are exclusively and alternately selectable. The switching device 14 includes a carrier 25, a contactor 26, a first terminal 27, a second terminal 28, and a third terminal 29.
The carrier includes an orientation axis X, a post 30, and a contact surface 32. The orientation axis X references the angular orientation of the carrier 25 and the contactor 26.
Referring to FIGS. 1A and 1B, the post 30 is centrally disposed through the carrier 25 and engages the holes 24 in the housing 12, so that the carrier 25 is rotatably mounted to the housing 12. The post 30 is aligned with the operational axis OA.
The contact surface 32 generally has a w-shape, with a peak P and two valleys V1, V2 joining at the peak P. Each state of the switching device 14 corresponds to one of the valleys V1 or V2 on the carrier 25.
The copper contactor 26 is fixedly coupled to the carrier 25 and includes two spaced protrusions 26a. The terminals 27, 28, and 29 are also copper and are mounted on the housing so that they can be engaged by the contactor 26. The first terminal 27 is positioned to the left of the axis OA. The second and third terminals 28 and 29 are aligned one above the other to the right of the axis OA.
The actuator mechanism 16 includes a housing structure 34, an actuator member 36, and a helical compression spring 38.
The housing structure 34 includes a housing cup 40 and a cap 42. The housing cup 40 is a tube shaped structure having a cylindrical cavity 44, an open end 46 as shown in FIG. 1A, an opposed end wall 48, and a plurality of retention holes 50.
The end wall 48 has an aperture 52 centrally disposed therethrough. The end wall 48 further has an internal flat seating surface 54 which circumscribes the aperture 52. The holes 50 are circumferentially spaced adjacent the open end 46.
The actuator member 36 includes a torus shaped actuator base 56, and an actuator arm 58 extending from the base 56. The base 56 has two flat surfaces. The arm 58 has a center axis C which extends along the arm lengthwise. The actuator member 36 is disposed in the housing cup 40. The arm 58 extends through the aperture 52, and the base 56 rests against the seating surface 54. The helical compression spring 38 rests on the base 56.
The cap 42 includes a top 60 and a cylindrically shaped body 62 extending from the top 60, so that the cap 42 is generally T-shaped.
The cap 42 is disposed on the housing cup 40, so that the top 60 covers the housing cup 40, and the body 62 partially extends into the cavity 44. The protrusions 64 on the cap 42 extend into the holes 50 in the housing cup 40, so that the cap 42 is secured to the cup 40. The body 62 includes circumferentially spaced protrusions 64 and a reaction surface 66.
The reaction surface 66 physically limits how far the spring 38 and actuator member 36 can recede into the cavity 44. The spring 38 seats against the reaction surface 66, and exerts a force on the actuator base 56, urging the lower surface of the actuator base 56 into contact against the seating surface 54.
The housing cup 40 is inserted into the bore 22 of the housing 12. The actuator member is in a center or neutral position, which means the spring 38 has caused the center axis C of the actuator arm 58 to be aligned with the axis TA. The actuator member is in an off-center position when the axis C is not aligned with the axis TA.
The user interface (not shown) can be any means appropriate for effectuating the necessary translation of the actuator mechanism 16 to be discussed below. The effort applied by the user interface on the actuator mechanism is illustrated by the arrow UI. For example, the user interface can be a push button or a lever, which connects to the cap 42 in a conventional manner.
Referring to FIG. 1B, unactuated the actuator mechanism 16 has an initial position A1. The carrier 25 has an initial position C1, where peak P is to the right of the translational axis TA. In these initial positions the actuator mechanism 16 is in a retracted position, so that the actuator arm 58 is centered and spaced from the carrier 25.
Referring to FIGS. 1A and 1C, application of effort UI by the user interface (not shown) causes axial motion of the housing structure 34 along the axis TA, as represented by the arrow M. The actuator arm 58 engages the sloped contact surface 32 on the carrier 25, slides into the valley V1, and exerts a force on the carrier 25, via the valley V1. The carrier 25 and the contactor 26 rotate in the direction of the valley V1, as illustrated by the arrow R.. to a position C2. The peak P has rotated from right side of axis TA to the left side. The center axis C of the actuator arm 58 is not aligned with the translational axis, and the base 56 is spaced from the seating surface 54. This causes the switch to be in its first state, where the protrusions 26a of the contactor 26 are in contact with the first and third terminals 27 and 29. Thus, making a first electrical connection between the terminals 27 and 29, and other electrical components (not shown). Thus, the carrier 25 translates force provided by the actuator mechanism 16 along the axis TA to a force operating with respect to the axis OA.
When the user interface (not shown) is released, the housing structure 34 will retract along axis TA and return to its initial position A1 (as shown in FIG. 1D). The actuator member 36 will be urged by the spring 38 to return to the centered position. However, the carrier will remain in position C2.
Due to previous rotation of the carrier 25, the peak P is to the left side of the axis TA. Referring to FIG. 1E, a subsequent actuation by applying effort UI, will again cause the housing structure 34 to move along the axis TA. The actuator arm 58 engages the contact surface 32, slides into the valley V2, and exerts a force to rotate the carrier 25 and the contactor 26 in a direction R2 to position C1. The peak P is to the right of the translational axis TA. The center axis C of the actuator arm 58 is not aligned with the translational axis TA, and the base 56 is spaced from the seating surface 54. This causes the switch to be in its second state, where the protrusions 26a of the contactor 26 are in contact with the first and second terminals 27 and 28. Thus, making a second electrical connection between the terminals 27 and 28, and other electrical components (not shown).
Upon release of the user interface UI, the housing structure 34 will retract from the carrier 25 to its initial position A1, and the actuator member 36 will again return to the centered position. The carrier 25 will remain in the initial position C1.
Successive actuations will bring about alternate selection of the carrier and contactor's two positions C1 and C2 in the above described manner, consequently causing alternate engagement of the two states of the switching device 14 (as shown in FIG. 1A). The actuator member 36 will return to the initial and centered position after each switch actuation.
The conventional actuation mechanism 16 has undesirable results when used. Referring to FIGS. 1C and D, after each actuation, when the housing structure 34 retracts from the carrier 25 and the actuator member 36 returns to its centered position, there is an audible noise. This noise results from the actuator base 56 being forced by the spring 38 back against the seating surface 34.
As the level of noise generated is dependent upon the amount of force exerted by the spring 38, the noise could be lessened by using a less powerful spring. However, the spring 38 must meet minimum functional requirements such that it is strong enough to reseat the actuator base 56, and it is sturdy enough to withstand repetitive actuations associated with normal use. Use of a weaker spring would decrease the functional capability of the spring. A dampening lubricant can also be used to minimize noise. This switch is generally in an environment where its noisy operation will be readily discernible to the user, which may contribute to a lack of perceived quality by the customer.
Referring to FIG. 1B, the disc shape of the actuator base 56 allows for off-center seating when in the unactuated position. The disc must necessarily be of smaller dimensions than the cavity 44 which contains it, so as to allow unrestricted travel of the actuator base 56 during actuation. As a result, the small disk may return after actuation to an off-centered position.
Consequently, off-center seating results in a differential in required actuation efforts, where it will randomly require more or less effort on the user interface (not shown) for switch actuation. The effort required will be depend on the position of the actuator member 36 relative to the translational axis TA. As the actuator member 36 seats farther from the translational axis TA, the efforts required increase proportionately. This differential in actuation efforts is noticeable to the user and is an objectionable characteristic.
Assembly of the actuator mechanism 16 is also difficult. The design of the actuator mechanism requires that the actuator member 36 is oriented concentrically within the cavity 44, such that the actuator arm 58 aligns with the aperture 52 in the housing cup 40. Achieving the proper positioning is time consuming, and increases assembly cost.
Therefore what is needed in the art is an improved actuation mechanism, which emits minimal noise during operation, increases accuracy in center repositioning subsequent to actuation, and further, a simplified assembly process.